Sharif Digital Repository

The development of an oil field plays an important role in the optimum production. In the past, several wells have been used in a multi layer reservoir to produce oil from each layer. It costs oil industry billions of dollars and the problem would be more severe in the offshore. Nowadays, one well can produce oil from different pay zones in a reservoir. In this type of well called smart or intelligent well, production tubing is in common between pay zones and some chokes are installed on the tubing to produce oil from different layers. The size of choke usually varies and can be controlled by an electrical system installed in the well. As each pay interval has different capacity in terms of... 

Management decisions, enhanced oil recovery, and reservoir development plans in petroleum industries are based on predictions by reservoir simulation. Due to uncertainties in model parameters or engineering assumptions, the simulation results are not accurate, while they are correct. For more accurate estimation of unknown production quantities, it is required to characterize the unknown parameters and its uncertainty. By using static data alone the result of characterization is unreliable and unsure, therefore dynamic data use practically. In reservoir engineering literature, this is called “History Matching”.The ensemble Kalman filter is an optimal recursive data processing algorithm based... 

After primary and secondary recovery processes more than 50 percent of oil remains in reservoirs. Therefore for more recovery from these reservoirs, methods of enhanced oil recovery should be applied.In this paper the effect of nanoparticles of SiO2 in size of 14 nm, on wettability is investigated. Using this nanoparticle, the wettability of carbonate rock in reservoirs could be changed and alter from oil-wet or mix-wet to water-wet. To assess this, hydrophilic changes of sandstone core and carbonate core are studied using the contact angle test. The same test is done on the carbonate core saturated with brine and oil that had received injection with brine and nanoparticles of SiO2 with two... 

Reservoir lifetime optimization is an important issue. The policies that are used for maximum production using optimization methods become challenging in the presence of uncertainty. Robust Optimization (RO) method is a technique to deal with uncertainty. Because of insufficient data, uncertainty is an inherent characteristic of reservoir model. This leads to inexact solutions of an optimization problem. Also, design based on uncertainty in economic parameters, especially uncertain oil price is a challenging issue. Taking the uncertainty explicitly is a solution when there is no measurement available. To take into account uncertainty several possible values (realizations) for the uncertainty... 

In recent years, due to the development of smart wells, optimization of waterflooding by injection/production rate control has receivedsome interests. We can postpone breakthrough time and increase the sweep efficiency by using inflow control valves (ICV). Due to complexity of reservoirs, existence of constraints and numerous influencing parameters, we need a robust and suitable optimization approach to overcome such problems. In this thesis, model predictive control (MPC) is chosen to be our optimization approach. MPC is suitable for constrained multi variable functions. Genetic algorithm is was chosenas optimizer. Eclipse reservoir simulator was used for reservoir simulation. Eclipse input... 

Excessive water production in highly heterogeneous mature reservoirs (water flooded or affected by water zones) leads to increased production costs. Water production causes sediment formation, creation of corrosion, water treatment and disposal, and finally due to the inefficiency of production, it leads to closure of the well.Among the methods introduced to reduce water production, the use of polymers and gels as an affordable and effective method has been widely used in enhanced oil recovery processes. The main mechanism in this method is blocking or limiting the major paths of water flow (fractures or high permeability zones) and thereby increasing sweep efficiency in water injection.... 

In this research oil production decline curve of heterogonous reservoirs was investigated. Heterogeneity is modeled by percolation theory and using Petrel software and mass balance equations are solved by Eclipse simulation software. In primary production stage which oil flows up the reservoir spontaneously by reservoir high internal pressure, decline curve is exponential. Changes in the characteristic parameter of the exponential decline curve with occupation probability and permeable objects size were investigated.In secondary production stage, after reducing the natural production potential of the reservoir, water injection is used to increase and stabilize the pressure and increase the... 

Asphaltenes are a polydisperse mixture of the heaviest and most polarizable fractions of the crude oil. They are defined according to their solubility properties as being soluble in aromatic solvents but insoluble in light paraffin solvents. Asphaltenes are usually responsible for many problems like wettability changes of the reservoir rock, pore clogging in the reservoir porous matrix and fouling in wellbore tubing and production surface facilities. Most of the studies in the literature, addressing the asphaltene precipitation and deposition (APD), are investigating natural depletion or gas injection process such as CO2 flooding. These studies show that asphaltene deposition and... 

In water drive or waterflooded reservoirs, a significant amount of oil is remained in the reservoir as the residual oil. A process known as gas assisted gravity drainage, in its tertiary mode, has been applied in a number of conventional reservoirs to recover this residual oil. Gravity drainage is the main mechanism of oil recovery in the gas assisted gravity drainage enhanced oil recovery process. Previous investigations has shown that gravity force, spreading coefficient, three phase capillary pressure and reservoir wettability have significant effect on oil recovered via this process. The feasibility of using such a process in a naturally fractured reservoir is investigated in this work... 

Gravity Drainage and Capillary Imbibition are among the most important mechanisms in oil production from carbonate fractured reservoirs. In order to investigate the feasibility and effects of these mechanisms in oil recovery from carbonate cores, some different experiments were carried out at Sharif University Laboratories. Carbonate cores were taken away from the well-known Asmari outcrop, Asmari Mountain in south east of M.I.S. city and used in these experiments. Oil and gas samples were collected from field separators and recombined to reservoir composition. The Gas-Oil ratio was adjusted to obtain the reservoir fluid properties. A core flooding apparatus with various capabilities was... 

Water flooding is one of the improved oil recovery methods that has been used for past decades. The water flooding efficiency is calculated in two different scale; macroscopic scale and microscopic scale. The efficiency in macroscopic scale is called volume sweep efficiency (Ev) and in microscopic scale, displacement sweep efficiency (Ed). A special type of hydrocarbon reservoirs are composed of several permeable units in an impermeable shaley background in a way that hydrocarbon can just flow through the permeable units. The predominant feature of such reservoirs is continuity of permeable units that affecting the flow behavior. This simplification enables us to model such reservoirs by... 

Due to the decrease in oil reserves in the world, increasing population and the growing demands for oil consumption in the world, increasing the oil recovery from oil reservoirs has become more important. Increasing the amount of oil production efficiency by using low salinity water/modified salinity water has been highly appreciated during the last two decades. Low-salt water is a new method, due to its advantages such as low cost, simplicity of operation and low environmental hazards. It is believed that low salinity water can alter the rock wettability from a more oil-wetting state to a more water-wetting state. In order to be able to predict the performance of low salinity water... 

Oil composition plays an undeniable role on the low salinity water flooding (LSWF) efficiency. This property directly affects the kinetics of wettability alteration through electrostatic interactions and interfacial tension (IFT). For instance, mixing in stagnant zones through a thin water film is considered as one of the most important diffusion controlled phenomenon which is goverened by Non-Fickian solute transport model. The major two potentials controlling the solute transport in thin film are salinity gradient and electrostatic potentials, which can be affected by oil composition and surface charges. This study aims to investigate the effect of oil composition on low salinity... 

Polymer flooding is a famous enhanced oil recovery method and is used to reduce mobility ratio of displacing fluid to displaced fluid by forming a stable front in displacing process. Due to high costs, polymer flooding faces economical risks and from this point of view, performance investigation of polymer flooding in laboratory scale was concerned. In this project, performance of 7 types of polymers which have different rheological properties were investigated in fractured/non-fractured carbonated and sandstone reservoirs. These polymers consists of 4 commercial polymers, one branched polymer, one synthetic polymer and one polymer composite which have different molecular weight,... 

Water in oil emulsion usually forms during natural water encroachment or enhanced oil recovery processes due to the reaction between asphaltenic and naphthenic acid part of oil with brine in some heavy oil reservoirs. This results in major production challenges because of high w/o emulsion viscosity which leads to significant pressure drops. Therefore, it is essential to investigate the dominant mechanisms of w/o emulsion flow in porous media to overcome the production challenges. In the present study, w/o emulsion behavior is investigated through both static and dynamic tests. The w/o emulsion was prepared through mixing of a crude with brine using magnet stirrer. Emulsion stability... 

Most of Iranian oil reservoirs, usually fractured carbonate, are in the end of primary or secondary recovery. Enhanced oil recovery methods are required for obtaining more performance from these resources. It seems to obtain more oil from reservoirs by flooding polymer after water flooding due to persistence of polymer effect, so the cost remain low. In this project, at the first the theory of water flooding and polymer flooding is described and after that we have done the following steps: •Injection of water into the plugs and calculate secondary recovery •Injection of polymer samples with 700 ppm concentration into the plugs •Injection of polymer samples with 1500 ppm concentration into... 

Visual investigation of the low salinity water injection into micromodel is the goal of this research. Although many researches have been performed to realize the dominating mechanism behind the increased oil recovery after low salinity water injection, many contradictions exist among the studies. Mechanisms are generally divided into two classes. One class is due to fluid/fluid interactions and the other one is due to fluid/rock interactions. A comprehensive set of experiments are conducted in this study to find out the dominating mechanism behind low salinity water injection under the existing conditions of the experiments. Effect of different wettability condition and presence and absence... 

Inorganic scale deposition has been found to affect many industrial processes,including water injection into the oil reservoirs. Major formation damage because of incompatibility of high sulfate ion content of seawater with formation water containing calcium ion results in formation damage and production decline.In this study, several simultaneous techniques are utilized for qualitative and quantitative analysis of calcium sulfate scale to get more insight into the damage of formation during smart water flooding at micro and Nano scales. In the experimental section, calcium sulfate deposition due to the mixing of the formation water and seawater samples was investigated using the dynamic... 

Oil and gas reservoirs in various parts of the world have declined over time, despite a high percentage of oil. Due to the increasing need for hydrocarbon resources, the need for more cost-efficient harvesting methods and less environmental damage is felt. Injection of saline water is one of the most cost-effective ways of harvesting due to the need for no expensive additives. On the other hand, microscopic glass modeling can be used to better understand and understand the performance of saline water at the microscopic scale. In this study we have been able to visualize the effective factors in infusion of saline water. Improved interfacial tensile and particle migration in kaolin-coated... 

Recent experimental studies have demonstrated that the lowering of brine could alter the wettability of the oil-brine-rock systems from an oil-wetting state toward a more water-wetting state. This so-called “Low-salinity effect” (LSE) is one of the main effects of the enhanced oil recovery technology based on low-salinity waterflooding. “Double layer expansion” (DLE) in the thin brine film is proposed as the principal mechanism of this phenomenon. Nonetheless, the role of the electrical behavior of the oil/brine and rock/brine interfaces on the kinetics and dynamics of this process is not well understood. Moreover, since most of the previous works have either dealt with a thin film at...